A new age-progression drawing of a baby stolen from a Chicago hospital 49 years ago could provide important clues in a mystery that has produced both hope and heartache for the family of the infant, named Paul Fronczak at birth.

The baby was taken from the arms of his mother, Dora Fronczak, by a woman posing as a nurse at Chicago's Michael Reese hospital in 1964.

The case had been considered closed by the FBI until two months ago when DNA tests revealed a child discovered by police in New Jersey in 1965 and raised by Chester and Dora Fronczak as Paul was not, in fact, the stolen child. The FBI has now re-opened its investigation into the kidnapping.

The aged-progression image was commissioned by ABC News "20/20" working in conjunction with the man who grew up as Paul Fronczak, now 49 and living in Nevada.

The likeness was created by artists at a Michigan firm, Phojoe, that works with families and law enforcement to solve crimes and locate missing relatives.

The artists used a photo taken of the infant a day after he was born and used family photos of Paul's father and brother to create the age-progression image.

"Let's hope he's sitting on his couch and sees this image and realizes it's him," said Emanuel Craciunescu, the president of Phojoe.

"It's tough working from just a baby photo taken at one day old, but I think this is pretty close," said Jovey Hayes, the age progression artist who created the image using photos of the parents and their other son, David Fronczak, who was born after his brother disappeared.

The man raised as Paul Fronczak said he hopes the drawing will help determine if the "real" or the "other" Paul Fronczak is alive and, if so, reunite him with his now-elderly parents who still live in Chicago.

"I would want nothing more than to have them be able to meet or at least know what happened to their real child before they're gone," Fronczak told ABC News.

Fronczak will be the subject of a "20/20" primetime special with Barbara Walters that will include reports by Chief Investigative Correspondent Brian Ross and the ABC News Investigative Unit.

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